Exhaust muffler



J. J. BowEs EXHAUS T MUFFLER Filed Dec.

Feb. 24, 1931.

Patented Feb. 24, 19.31

PATENT FFICE JOI-IN J'. BOWES, 0F MIAMI, FLORIDA EXHAUST IvIUFFLER Application led December 14, 1929. Serial No. 414,097.

This invention relates to exhaust mufllers for explosion motors, such as the motors of automobiles, aircraft, etc., and is more particularly concerned with the provision of a muffler of relatively simple construction effective to scavenge the motor cylinders by complete exhaustion of gases and to reduce the noise of discharge of the exhaust gases, without creating back pressure.

In carrying out my invention, a succession of alining tubes are utilized to increase the rate of discharge flow of the gases, and means are provided to produce forced draft air streams to cooperate therewith to increase tube created suction and coincidentally to cool and cause contraction of the gases passing through the tubes and thereby eliminate back pressure.

The invention consists in the constructions,

arrangements and combinations of parts hereinafter described and claimed and will be more clearly apparent from the following detailed description which is to be read in conjunction With the accompanying drawings in which Figure l is a view in top plan of the muffler of the present invention.

Figure 2 is a longitudinal vertical section through the muffler taken -on line 2-2 of Figure l.

Figure 3 is an end elevation of the intake' end of the muffler. v i

Figure 4 is a fragmentary longitudinal sectional view of a modiiied form.

Reference to the drawings will show that the mufier is provided with an outer tubular shell or casing l, which may be circular or oval in cross section as desired, and which tapers inwardly from an intake end 2 of maximum diameter to a discharge end 3 of uniform but relatively less diameter.

Adjacent to its discharge end 3, a band 4 is fixed externally to the casing and supports through a plurality of spacing legs 4 an air injector 5 formed substantially as a hollow sion 6 from the rear end of the truncated cone Athe shell.

l/Vithin the outer casing l and spaced therefrom is a long Venturi tube 7 extending from the intake end 2 to a point adjacent but inwardly of the discharge end 3 of the shell. This Venturi tube is intended -to receive the exhaust motor gas through an appropriate conduit connection to its intake end 8. It is centered within the shell by a plurality of radial spacing legs 9 supporting its intake end 8 from the interior of the shell at its intake end 2, and by a series of radial spacing legs l0 similarly supporting the discharge end olf1 tlllie Venturi tube from the interior of the s `e The Venturi tube 7 tapers in opposite directions from an intermediate point of maximum diameter. That portion of the tube between its discharge end and said intermediate point houses a perforated baffle cone 11 of truncated form decreasing in diameter toward the discharge end of the Venturi tube and spaced from its sides. As shown, the cone is appropriately ixed at its larger end to the interior of the Venturi tube at said intermediate point of maximum diameter.

The Venturi tube 7 is positioned within the shell with its discharge end terminating adjacentv but appreciably inwardly of the discharge end 8 of the shell and appreoiably spaced from the walls thereof and extending partly within the intake end of a second relatively short tube 12 constituting a Venturi tube. rlhis second venturi has its exterior formed to correspond to the uniform diameter and cross section of the discharge end 3 of the shell. lt is adjustably fixed therein vby means of a lag screw 13 passing through cone therein, are cooled and contract through the effect of the stream of air which passes `through the outer shell 1' over the venturi.

'lhis cooling air stream, with the motor vehicle.v o1' air craft in motion, isa forced draft of high cooling power and substantial force. Even with the land or'air vehicle stationary, a forced draft of less intensity is created by the back wash from the plane propeller ora from the usual cooling fan of the land vehicle. The cooling action ofthis draft on the Venturi tube and on the hot exhaust gases passing therethrough will have the effect of causing contraction of these gases in offset of back pressure caused by the baiiie cone.

As the partially cooled gases exit from the elongated tubular cooling element 7 into theintake endof the Venturi tube 12, their speed is accelerated and they arefurther cooled by the injection of the forced draft air stream passing `therewith into the intake of venturi 12 over the exteriorof the discharge end of tube 7, which air stream is rovided by the annular conduit formed by t e space between the interior of shell l and the exterior. of tube 7.

Asv the cooled and broken up gases exit from the venturi 12 and from the exit end 3 of the shell 1 which in effect is the exit end of venturi 12 and nests in the intake end of cone 5, they are'ejected from the nozzle 6 of the .external'terminal cone 5 on the shell at an accelerated speed by a second forced draft air stream passing over the exterior ofthe shell and into the interior of the terminal cone 5, which constitutes in effect, an aspirating air cooled discharge nozzle.

Thus the aspirating action of these forced draft air streams not only tends to create suction and muiiie the noise of explosion, but accelerates the passage of the exhaust gases, offsetting back pressure and effecting thorough scavenging of the cylinders, but thoriss ' oughly -breaks up and cools the' gases at the exit end of the muier shell.

The described construction ha`s the advan-` tage of combining simplicity and relatively low cost of construction with effective oper` ation. The ad'ustment provided for the venturi l2 has t e added advantage of per-` the first Venturil tube 7 to the speediof the .exhaust gases discharging from tube 7 into the venturi 12.

It will be noted that the tubes 7 and 12 constitute in effect a succession of alined Venturi tubes with the discharge end of the first tube nesting in and spaced from thek interior of the intake end of the next succeeding tube to provide annular injection openings and that an air conduit passes a stream of air through `said annular opening with the gases further-cooled and diffused by the second air stream injected -therein at the nozzle of the discharge cone.

At the intake'end of the muffler, the gas and air receivi fr functions of the tube 7 andshellv 1 may e reversed. In the modified form shown -in Figure 4 of the drawings, the first tube 7 a is used as the first air stream conduit, its intake end being tapered outat its intake end. With this.` arrangement,`

the hot exhaust gases are cooled by air streams externally of casing 1a and internally of tube 7a between which streams the ex-` haust gases pass.

While the illustrated structures represent preferred forms of the invention,` they are intended as illustrative rather than restrictive thereof, and are subject to change and modification in adaptation to different conditions of manufacture and use in consonsoy nance with the spirit of the invention and the scope of the appended claims.

What I claim, therefore, and desire to secure by Letters Patent is:

1. A muffler for exhaust gases of explosive motors comprising a series of nested tubes with the discharge ends of those tubes lforwardly of the terminal' tube nesting in and spaced from the interior of the intake ends of the next succeeding tube to providev annular air injection openings therebetween, and

j annular air conduits externallyof said forward tubes having discharge ends communieating with said annular air injection openings, the first tube of said series having its intake end arranged to receive exhaust gases therein andf having mounted on its interior a perforatel conical baille pr viding a discharge jet at its rear end directed toward the discharge end of said first tube.

2. A muier for the exhaust gases of explosive motors comprising a tubular outer casing tapering from an intake end of maximum diameter to a discharge end of reduced and uniform diameter, an elongated tubular intake conduit supported within said casing in spaced relation thereto providing an annular conduit therebetween and extending from its intake end toward the discharge end of said casing, a Venturi tube seated within and contacting the interiorof the casing adjacent to its discharge end with the intake end of said Venturi tube of' greater internal diameter than the exterior of the discharge end of said conduit and extending partially thereover to provide an aspirating passage therebetween communicating with said annular conduit, means for adjusting said Venturi tube longitudinally of the outer casing to vary the position of its intake end relatively to the discharge end of said tubular intake conduit for varying the arca ot said aspirating passage.

3. A muffler 'for the exhaust gases of explosive motors comprising an open ended tubular outer casing tapering from an intake end of maximum diameter to a discharge end of reduced diameter, an elongated gas receiving tube supported Within said casing in spaced relation thereto to provide an annular air passage therebetween and extending from the intake end of said casing toward its discharge end, a perforate truncated conical baiiie mounted within said elongated tube with its rear end providing a discharge jet positioned forwardly ofthe discharge end of said tube, a Venturi tube seated within said casing at its discharge end and engaging the walls thereof with the intake end of said Venturi tube of greater internal diameter than the exterior of the discharge end of the gas receiving tube and extending partially thereover to provide an aspirating air passage therebetween communicating with the dis-V charge end of the annular air passage between said casing and irst tube.`

4. A muiler for the exhaust gases of explo` sive motors comprising an open ended tubular outer casing tapering Jfrom an intake end of maximum diameter to a discharge end of reduced diameter, an elongated gas receiving v tube supported within said casing in spaced relation thereto to provide an annular air passage therebetween and extending from the intake end of said casing toward its discharge end, a perforate conical bafiie suspended within said elongated tube, a Venturi tube seated within said casing at its discharge end and engaging the walls thereof with the intake end of said Venturi tube of greater internal diameter than the exterior of the discharge end of the'gas receiving tube and extending partially thereover to provide an aspirating air passage therebetween communicating with the discharge end of the annular air passage between said casing and first tube, and a third tube mounted externally over and spaced from the discharge end of the outer casing and tapering into aline ment with the Venturi tube and provided with a discharge nozzle spaced rearwardly from and alined with the discharge end of said Venturi tube to provide a second aspirating air passage communicating with the discharge end of the air passage between the exterior of the discharge end of the outer casing and the spaced overlying portion of the third tube.

5. A muiier for the exhaust gases of explosive motors comprising 'an open ended tubular outer casing tapering from an intake end of a maximum diameter to a discharge end of reduced diameter, an elongated gas receiving tube supported in said casing in spaced relation thereto to provide an annular air passage therebetween and extending from the intake end of said casing toward its discharge end, a Venturi tube fitted within said casing adjacent its discharge end and engaging the walls thereof, the intake end of said Venturi tube being of greater internal diameter than the exterior of the discharge end of the gas receiving tube to provide an aspirating air passage therebetween communicating with the discharge end of the annular air passage between said casing and said receiving tube, and a third tube mounted externally of and spaced from the discharge end of the outer casing and tapered into substantial alinement with said discharge end to provide a second aspirating air passage communicating with the discharge end of the air passage between the exterior ot the discharge end of the outer casing and the spaced overlying portion of the third tube.

JOHN J. BOWES. 

